ES2953580T3 - Electronic device equipped with a self-diagnosis function - Google Patents

Abstract

This electronic device includes a self-diagnosis module (22) capable of: - activating a timer in response to the transition of a discrete electrical signal, generated by a generator, from a first stable state to another state, this timer counting a period of time default since activated; and - once the period of time counted by the timer has elapsed, compare the current state of the discrete electrical signal with the first stable state; and - if the current state is equal to the first stable state, causing the generation of an error signal and, conversely, if the current state is different from the first stable state, preventing this activation of the error signal. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Electronic device equipped with a self-diagnosis function

The invention relates to a set including an electronic device equipped with a self-diagnosis function. The invention also relates to:

- a self-diagnosis module for the realization of this electronic device,

- a self-diagnosis procedure, and

- a registration support for the implementation of this procedure.

Known electronic devices equipped with a self-diagnosis function include:

- a generator capable of generating at an output a discrete electrical signal that can only take, at a given instant, a single stable state from among a discrete set of possible stable states, this discrete set being chosen from the group consisting of a discrete set of several stable voltages and of a discrete set of several stable current intensities, this discrete set of possible stable states comprising a first and a second predetermined stable states,

- a self-diagnosis module capable of generating an error signal that indicates a failure, this self-diagnosis module being able to generate this error signal when connected only to the output of the generator.

Detectors of very short electrical impulses are also known from document US4857760A. However, these detectors are not used to detect and indicate early signs of failure.

Generally, the generator is made up of electronic components mounted on a printed circuit. Over time, electronic components and printed circuit boards are subjected to numerous external stresses, such as thermal and mechanical stresses. These external stresses end up wearing out the electronic components and the electrical tracks of the printed circuit. This progressive wear of the electronic components of the printed circuit ends up causing a breakdown of the generator that permanently interrupts its operation. The self-diagnosis module allows you to detect this definitive fault.

However, it would be preferable if the self-diagnosis module could signal an error even before definitive generator failure occurs. In fact, this is desirable to be able to establish preventive maintenance interventions, to prevent this generator from breaking down permanently. Furthermore, such a self-diagnosis module must remain easy to perform.

Therefore, the subject of the invention is a set that includes an electronic device of this type according to claim 1.

Embodiments of this set may include one or more of the features of the dependent claims.

The invention also has as its object a self-diagnosis procedure implemented by the claimed electronic device.

Finally, the invention also has as its object an information recording medium readable by a microprocessor to implement the claimed procedure.

The invention will be better understood by reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

Figure 1 is a schematic illustration of an electronic device equipped with a self-diagnosis function;

Figure 2 is a schematic illustration of a first embodiment of a self-diagnosis module for the electronic device of Figure 1;

Figure 3 is a flow chart of a self-diagnosis procedure implemented in the electronic device of Figure 1;

Figures 4 and 5 are graphs illustrating the evolution over time of various electrical signals of the self-diagnosis module of Figure 2;

Figure 6 is a schematic illustration of another embodiment of an electronic device equipped with a self-diagnosis function;

Figure 7 is a schematic illustration of another embodiment of the self-diagnosis module of Figure 2.

Chapter I: Notations and definitions:

In the figures the same references are used to designate the same elements.

In the remainder of this description, features and functions well known to those skilled in the art are not described in detail.

A "discrete" electrical signal is an electrical signal that cannot take, at a given instant, more than a single stable state from among a predetermined discrete set of several possible stable states. This discrete electrical signal can adopt each of the stable states of the predetermined discrete set over time. On the contrary, this discrete electrical signal cannot adopt a stable state that is not part of this predetermined discrete set. The discrete set includes a limited and limited number of possible stable states.

By "steady state" we designate a value of the discrete electrical signal that can be kept constant for a period of time longer than the transition time 5t required to go from one stable state to another stable state. By "longer period" is designated a period at least twice, and preferably ten times or one hundred times, greater than the time 5t. For example, this period is greater than 1 s, or 5 s, or 10 s, or 1 min.

By “connecting”, the act of electrically connecting is designated.

An “untimely switching” of a discrete electrical signal is an accidental tilting of an initial stable state of this discrete electrical signal towards another state followed immediately by a return to this initial state. An untimely switching is very short, that is, the swing from the initial stable state to the other state and then the return to the initial stable state occurs in a very short time interval Ac. The interval Ac is less than the smallest interval Amin of time during which the discrete electrical signal can maintain the same stable state in the absence of a fault and during normal operation. Typically, the Ac range is less than Amin/2 or less than Amin/10 or Amin/100. Typically, the interval Ac is less than 1 s and often less than 500 gs, or 100 gs, or 50 gs.

An "untimely pulse" is an untimely switching of the discrete electrical signal during which the state of the discrete electrical signal passes from an initial stable state to a higher state before returning to this initial stable state. The higher state corresponds to a value of the electrical signal higher than that in the initial stable state. The highest state may be another higher stable state or a higher unstable state.

Here, "unstable state" refers to a state of the discrete electrical signal that does not belong to the predetermined discrete set of possible stable states for this discrete electrical signal.

An "untimely cut" is an untimely switching of the discrete electrical signal during which the value of the discrete electrical signal changes from an initial stable state to a lower state before returning to its initial stable state. The lower state corresponds to a value of the electrical signal that is lower than that in the initial stable state. The lower state may be another lower stable state or a lower unstable state. Typically, very often, in the lowest state, the value of the discrete electrical signal is equal to 0 A or 0 Vdc.

Chapter II: Examples of embodiments:

Figure 1 represents an electronic device 2 of an aircraft. The aircraft is, for example, a plane or a helicopter. Device 2 is equipped:

- with two terminals 4 and 6 intended to be connected to an electrical power source 7,

- with an output 8 through which a discrete electrical signal SE ^g is emitted,

- with an output 10 through which a discrete diagnostic signal SE ^e is emitted that allows an error to be signaled based on the analysis of the signal SE ^g , and

- with an input 12 to receive a reset command.

In Figure 1, only the Vcc potential and the mass (0 Vdc) of the source 7 have been represented. The Vcc potential is a direct voltage. It is, for example, between 3 Vdc and 30 Vdc or between 3 Vdc and 50 Vdc. Here, the potential Vcc is equal to 30 Vdc. The source 7 is for example an electrical distribution network or a battery.

Terminal 4 is connected to the Vcc potential and terminal 6 is connected to ground.

In this embodiment, the signal SE ^g can take only two stable states. These two stable states are hereinafter referred to as "V ⁰ state" and "V ³⁰ state" respectively. In the states V ⁰ and V ³⁰ the values of the signal SE ^g are equal, respectively, to 0 Vdc and Vcc.

The SE ^e signal is also a discrete electrical signal. In this embodiment, it takes only two stable states V ⁰ and V ⁵ . The state V ⁰ of the signal SE ^e is the same as the state V ⁰ of the signal SE ^g . In the V ⁵ state, the value of the signal SE ^e is equal to 5 Vdc. In the absence of a fault, the signal SE ^e is in state V ⁵ . To signal an error, the signal SE ^e is in the state V ⁰ .

To generate the signals SE ^g and SE ^e , the device 2 includes, respectively, a generator 20 and a self-diagnosis module 22. The device 2 also includes a power supply stage 24 of the generator 20 and a power supply stage 26 of the module 22 as well as a power bus 28.

Bus 28 includes two electrical conductors 30 and 32 connected directly and permanently, respectively, to terminals 4 and 6.

Stage 24 is connected to conductors 30 and 32 and produces, from the potential difference between terminals 4 and 6, the voltage and current necessary to power and operate the generator 20. Stage 24 makes it possible to stabilize the power supply. of the generator 20 and, if necessary, deliver a supply voltage to the generator 20 higher or lower than the Vcc potential. To this end, stage 24 typically includes a printed circuit board and electronic components. Therefore, stage 24 is susceptible to failures that produce untimely cuts in the power supply of the generator 20 and therefore untimely cuts in the signal SE ^g .

For example, stage 24 includes a Zener diode and, optionally, one or more capacitors to stabilize the power supply to the generator 20. One skilled in the art knows how to implement such a power supply stage. Accordingly, step 24 is not described in further detail here.

Step 26 performs the same functions as step 24 but for module 22. Therefore, it is normally performed in the same way as step 24. Consequently, step 26 is not described here in more detail. Stage 26 is separate and independent from stage 24. In particular, stage 26 can operate correctly even if stage 24 fails. Furthermore, whatever failure affects the operation of stage 24, it has no impact on the operation of stage 26. For this, stages 24 and 26 are each carried out with the help of their own electronic components.

The generator 20 includes an output 36 at which the signal SE ^g is output. This output 36 is directly connected to output 8. In this example, the generator 20 is a detector of a physical quantity. The signal SE ^g is in the state V ³⁰ when the physical quantity crosses, in one direction, a predetermined threshold S ¹ . The signal SE ^g is in the state V ⁰ when this physical quantity crosses, in the opposite direction, a predetermined threshold S ² . Here, to simplify the understanding, the thresholds S ¹ and S ² are the same so that the generator 20 does not present hysteresis.

The physical magnitude detected can be of any nature. For example, and in a non-limiting way, this physical magnitude can be:

- an electrical physical quantity such as an electrical resistance, a current intensity or a voltage,

- a mechanical physical quantity such as a mechanical displacement of a part,

- a magnetic physical quantity such as the amplitude and/or direction of a magnetic field or an electric field, and

- an optical physical quantity such as luminous intensity.

The generator 20 typically includes a printed circuit board and electronic components. Thus, the generator 20, like the stage 24, is susceptible to failures that produce untimely impulses and untimely cuts of the signal SE ^g .

To generate the SE ^g signal, by way of illustration, the generator includes:

- a transducer 40 that converts the physical quantity into a continuous electrical signal representative of the value of this physical quantity, and

- a comparator 42 that compares the continuous electrical signal with the threshold S ¹ to generate the signal SE ^g .

The module 22 detects a failure of device 2 only from the analysis of the signal SE ^g . Here, the module 22 is therefore in particular capable of detecting a failure of the stage 24 and the generator 20. To do this, the module 22 detects untimely switching in the signal SE ^g . Indeed, such untimely switching is caused by the wear of electronic components and printed circuits and constitutes precursor signs of a permanent breakdown.

Module 22 includes:

- an input 44 connected to output 36 to receive the signal SE ^g to be analyzed,

- an output 46 through which the signal SE ^e is emitted, and

- a reset input 48 of module 22.

Output 46 is directly connected to output 10 of device 2. Input 48 is directly connected to input 12 of device 2. A detailed embodiment of module 22 is described with reference to Figure 2.

Here, all the printed circuits and electronic components of device 2 are housed within the same box 50. Box 50 is, for example, a waterproof box that protects the electronic components against dust and water. Typically, the protection rating of the enclosure 50 is equal to or better than the IP51 or IP62 rating. Here, by way of illustration, the electronic components of the generator 20, the module 22 and the stages 24 and 26 are mounted on the same printed circuit board.

Figure 1 shows that the outputs 8 and 10 and the input 12 are connected by wired links, respectively 52 to 54, to respective inputs and outputs of an electronic system 56 for processing the signals SE ^g and SE ^e . For example, system 56 is capable, from the signal SE ^g , of producing commands from other electrical elements of the aircraft. The system 56 is also capable of taking into account the SE ^e signal during the construction of commands for the other elements of the aircraft. For example, the system 56 determines from the signal SE ^g whether the signal SE ^g is reliable or not and in the event that the signal SE ^g is considered to be unreliable, the latter is ignored to construct the commands of others. aircraft elements. The system 56 also takes advantage of the signal SE ^e to indicate to a maintenance operator that the generator 20 and/or the stage 24 show precursor signs of failure.

System 56 is also capable of sending an initialization command to module 22 through link 54 and inputs 12 and 48. For example, this possibility is used to restart module 22 after it has detected an untimely switching without having You have to cut the power to module 22 to do this. After being reset, module 22 is again able to detect a new untimely switching.

Figure 2 represents an embodiment of module 22. Module 22 includes:

- a step 60 for shaping the signal SE ^g ,

- a step 62 to detect an untimely impulse,

- a step 64 to detect an untimely cut, and

- a stage 66 to generate the signal SE ^e .

Step 60 transforms the signal SE ^g into a shaped electrical signal SE ^mef . Here, the signal SE ^mef is identical to the signal SE ^g except that its two stable states are, respectively, the V ⁰ and V ⁵ states instead of the V ⁰ and V ³⁰ states. In addition, fitness also consists of obtaining an SE ^mef signal whose ascending and descending fronts are as vertical as possible.

Here, stage 60 includes:

- a resistor R2 connected between input 44 and the Vcc potential, and

- a MOSFET transistor (isolated grid field effect transistor) T1, the grid of which is connected directly to input 44.

The source of transistor T1 is connected to ground and its drain is connected to a potential of 5 Vdc through a resistor R1.

The drain of transistor T1 is also connected to an inverter U1.1 whose output delivers the signal SE ^mef .

Transistor T1 conducts if the voltage V ^gs between its grid and its source is greater than a predetermined threshold V ^th . On the contrary, if the voltage V ^gs is lower than the threshold V ^th , transistor T1 does not conduct. When transistor T1 conducts, current can flow through it from the drain to its source.

Step 62 generates an electrical signal SE ⁱ that is in state V ⁵ as long as an untimely impulse has not been detected. As soon as an untimely pulse is detected in the signal SE ^g , step 62 signals an error by immediately tilting the signal SE ⁱ to its stable state V ⁰ .

For this purpose, stage 62 includes a monostable scale U3.1, whose input B is connected directly to the output of the inverter U1.1. This U3.1 scale also includes an output Q at which a clock signal S ^h is output. The signal S ^h is a discrete electrical signal that can only take the two stable states V ⁰ and V ⁵ . The signal S ^h takes the state V ⁰ as long as the signal SE ^mef does not present a rising front. In response to a rising front in the signal SE ^mef , the signal S ^h changes from state V ⁰ to state V ⁵ and then remains in state V ⁵ for a time interval A3.1. When the interval A3.1 has elapsed, the signal S ^h automatically and systematically falls back to the state V ⁰

Here, scale U3.1 is a monostable scale that cannot be activated or reset. Thus, after having been activated by a first rising front of the signal SE ^mef , even if a second rising front occurs in the signal SE ^mef before the end of the interval A3.1, the instant at which the signal S ^h returns to state V ⁰ remains unchanged.

The interval A3.1 is greater than the interval Ac of an untimely impulse, that is, greater than the maximum duration of an untimely impulse. For example, here the interval A3.1 is greater than 50 ps or 100 ps. The interval A3.1 is also less than the interval Amin, that is, less than the minimum duration during which the electrical signal SE ^g maintains its state V ³⁰ . Here, the interval A3.1 is less than 1 s. For example, interval A3.1 is equal to 100 ps.

Stage 62 also includes a scale U4.1. The U4.1 scale is a JK scale. The J input of scale U4.1 is connected to the output of inverter U1.1 via an inverter U1.2. Input K is connected to ground. The clock signal input of scale U4.1 is directly connected to the Q output of scale U3.1 to receive the ^signal Sh .

The U4.1 scale also includes an RST input which is connected to input 48. This RST input is used to re-initialize the U4.1 scale and therefore to detect a new untimely pulse.

The scale U4.1 has an output 70 through which the signal SE ⁱ is output.

In response to a falling front in the signal S ^h , the scale U4.1 compares the current state of the electrical signal received at its input J with the current state received at its input K. If at this instant, the current states in the inputs J and K are, respectively, the states V ⁵ and V ⁰ , then the output 70 swings towards the state V ⁰ . On the contrary, if at this instant the current states of the inputs J and K are both equal to the state V ⁰ , then the output 70 retains its previous value. The U4.1 scale is therefore capable of memorizing the detection of an untimely impulse until it is reset.

Upon power-up or after a reset command received at its RST input, output 70 switches to the ^V5 state. Thus, as long as step 62 has not detected an untimely impulse, the signal SE ⁱ is in state V ⁵ . As soon as an unexpected impulse is detected, the state of the SE ⁱ signal switches to the V ⁰ state and remains in this V ⁰ state until the next power-up or until a reset command is received.

Step 64 generates a signal SE ^c in state V ⁵ as long as an untimely cut has not been detected. If an untimely cut is detected, step 64 signals this error by immediately toggling the signal SE ^c to its V ⁰ state. In this embodiment, step 64 is identical to step 62 except that it includes an additional inverter U1.3 that inverts the signal SE ^mef before it is transmitted to the monostable scale and the scale JK. In step 64, the scale U3.1, the scale U4.1 and the inverter U1.2 carry, respectively, the digital references U3.2, U4.2 and U1.4. Inverter input U1.3 is directly connected to inverter output U1.1 and its output is directly connected to scale input B U3.2 and inverter input U1.4. The interval A3.1 is called "interval A3.2" in the case of step 64. Here, the intervals A3.1 and A3.2 are the same.

Step 66 generates the electrical signal SE ^e from the electrical signals SE ⁱ and SE ^c . More specifically, step 66 toggles the signal SE ^e to the state V ⁰ as soon as at least one untimely pulse or untimely cut in the signal SE ^g is detected. To do this, stage 66 includes a logic gate U2.1 that generates at the output a signal that corresponds to the “NAND-AND” logic operation between the signals SE ⁱ and SE ^c . The output of gate U2.1 is connected to output 46 through an inverter U2.2.

In Figure 2, voltmeters VM0.2, VM0.3, VM1.0, VM1.1, VM1.2, VM2.0, VM2.1, VM2.2 and VM3.3 represent the locations where voltages are measured which carry the same numerical references in the graphs of figures 4 and 5. It will be observed that the voltages VM0.2, VM1.0, VM1.1, VM1.2, VM2.2 and VM3.0 correspond, respectively, to the signals SE ^g , SE ^mef , S ^h , SE ⁱ , SE ^c and SE ^e .

The operation of device 2 will now be described with the help of Figure 3 and the graphs in Figures 4 and 5.

In the graphs of Figures 4 and 5, the x-axis is graduated in seconds. The abscissa axis is common to the different electrical signals represented in each of the graphs. The ordinate axes are graduated in volts. A respective ordinate axis is associated with each electrical signal represented. Figures 4 and 5 correspond to the cases in which the generated SE ^g signals include, respectively, an untimely pulse and an untimely cut. The electrical signals represented in these figures correspond to those measured by the voltmeters marked in figure 2 with the help of the same numerical reference.

Initially, an initialization phase 78 is executed. This phase 78 is executed at least during the power-up of the module 22. During this phase 78, the scales U4.1 and U4.2 are initialized so that the signals SE ⁱ and SE ^c are in their states ^V5 .

Then, during a step 80, the generator 20 continuously generates the signal SE ^g as a function of the measured physical quantity.

In parallel, during a step 82, the signal SE ^g is acquired by the module 22 and put into shape by the step 60. The signal SE ^mef is transmitted to the detection steps 62 and 64.

During a step 84, in response to a rising front in the signal SE ^g , step 62 activates a timer that counts down the interval A3.1. Here, it is scale U3.1 that performs this timer function. In Figure 4, the activation of the timer occurs at a time t1.

Then, during a step 86, at the end of the interval A3.1, i.e. in Figure 4 at a time t ² , step 62 compares the current state of the signal SE ^g with its initial state, i.e. here in the state V ⁰ . This comparison is carried out here by the U4.1 scale.

If at time t ² the signal SE ^g is in the state V ⁰ , this means that it is an untimely impulse. In this case, during a step 88, the scale U4.1 tilts its output 70 towards the state V ⁰ . In response, always during step 88, the signal SE ^e also switches to state V ⁰ to signal the presence of this untimely impulse and therefore this failure to the treatment system 56.

On the contrary, if at instant t ² the current state of the signal SE ^g is the state V ⁵ , and therefore different from the state V ⁰ , this means that it is not an untimely impulse but rather a change of state of the signal SE ^g . In this case, the state of the SE ⁱ signal remains unchanged. Therefore, if no untimely pulse has been signaled so far, the signal SE ⁱ remains in the state V ⁵ . On the contrary, if an untimely impulse has already been detected, the signal SE ⁱ remains in the state V ⁰ .

Steps 82 to 88 are repeated in a loop.

In parallel with steps 84 to 88, during a step 90, in response to a falling front in the signal SE ^g , step 64 activates a timer that counts down the interval A3.2. Here, it is scale U3.2 that performs this timer function. In Figure 5, the activation of the timer occurs at time t ³ .

During a step 92, at the end of interval A3.2, i.e. in Figure 5 at time t ⁴ , step 64 compares the current state of the signal SE ^g with its initial state, i.e. here at state V ⁵ . This comparison is carried out by the U4.2 scale.

During a step 94, if at time t ⁴ , the current state of the signal SE ^g is the state V ⁵ , this means that it is an untimely cut. In this case, in response, scale U4.2 immediately changes its output to the V ⁰ state. In response, always during step 94, the signal SE ^e also changes to state V ⁰ to signal the presence of this untimely cut and therefore this failure to the system 56.

On the contrary, if at instant t ⁴ the current state of the signal SE ^g is the state V ⁰ , and therefore different from the state V ⁵ , this means that it is not an untimely cut but rather a change of state of the signal SE ^g . In this case, the state of the SE ^g signal remains unchanged. Therefore, if no untimely outage has been signaled so far, the signal SE ^c remains in state V ⁵ . On the contrary, if an untimely cut has already been detected, the SE ^c signal remains in the V ⁰ state.

Steps 90 to 94 are repeated in a loop.

In parallel with the preceding steps, during a step 100, the system 56 processes the signals SE ^g and SE ^e . For example, the signal SE ^g is used to control another element of the aircraft and the signal SE ^e is used to signal a failure of the generator 20 or the stage 24 that requires the implementation of a preventive maintenance operation.

Figure 6 represents an electronic device 110 equipped with a self-diagnosis function. Device 110 is identical to device 2 except that module 22 and feed stage 26 are remote in proximity to treatment system 56. In this case, the module 22 may be very far from the generator 20. For example, the module 22 is located more than 1 m or 10 m from the generator 20. In this embodiment, the module 22 and the stage 26 are no longer located within from box 50 but outside this box. Therefore, module 22 is mechanically independent of generator 20 in this embodiment. The module 22 can also be placed in the same box that contains the system 56, or can even be made on the same printed circuit board as the system 56. In this embodiment, the module 22 is also more sensitive to a failure in the wired link 52 connecting generator 20 to system 56.

Figure 7 shows a self-diagnosis module 120. This module 120 functions like module 22, except that it is made with the help of a programmable microprocessor 122 capable of executing instructions recorded in a memory 124. To do this, the memory 124 includes the instructions necessary for the execution of steps 82 to 94. of the procedure in Figure 3.

Chapter III: variants:

Variants of the self-diagnosis module:

In a variant, step 60 is omitted. This is possible, for example, if the signal SE ^g does not need to be shaped and can be transmitted directly to detection steps 62 and 64. For example, step 60 can be omitted here if the two stable states of the signal SE ^g are the states V ⁰ and V ⁵ .

The role of the ascending and descending fronts can be reversed. In this case, the self-diagnosis module must be adapted accordingly. For example, the timer can be activated on a falling front instead of a rising front. In this case, the monostable scale U3.1 is replaced by a monostable scale activated by a falling front and an inverter is introduced to invert only the electrical signal received at input B of this monostable scale. Similarly, the comparison performed by the JK scale may be triggered in response to a rising front and not in response to a falling front. In this case, the clock signal input of scale U4.1 is connected to the output Q of monostable scale U3.1.

In a variant, the signal SE ^g can take more than two different stable states. For example, the SE ^g signal takes more than three or four or five different stable states. In this case, for example, the shaping step is modified to convert the signal SE ^g that takes more than two stable states into a discrete electrical signal shaped SE ^mef that only takes two stable states. For example, in response to a rising front in the signal SE ^g , the SE ^mef changes from the V ⁰ state to the V ⁵ state. In response to a falling front in the SE signal ^g , the SE ^mef signal changes from the V ⁵ state to the V ⁰ state. This SE ^mef signal is then processed by steps 62 and 64 as described above.

Entries 12 and 48 and link 54 can be skipped. In this case, the module 22 cannot be automatically restarted after being powered up by the system 56. Consequently, if the module 22 has detected an untimely switching, as long as the power supply to the module 22 is not cut off, the signal SE ^e permanently signals this fault even if it has already disappeared.

In another embodiment, scale U3.1 or U3.2 or both can be replaced by monostable scales that can be reset or reactivated. In this case, every time a new rising front occurs in the SE ^mef signal, the timer is reset and activated again.

In a variant, the intervals A3.1 and A3.2 are different from each other. This can be useful if the Ac interval of an untimely pulse is different from the Ac interval of an untimely cut.

It is possible to simplify the module 22 so that it is only capable of detecting untimely pulses or only capable of detecting untimely cuts. For example, step 64 and step 66 are omitted and output 70 is connected directly to output 46. In this case, module 22 is only suitable for detecting an untimely pulse.

In the case of the 120 module, the SE ^g signal can be recorded to a digital file. The digital file is then transmitted and recorded, for example, in memory 124. Later, when the generator 20 no longer generates the signal SE ^g , the module 120 analyzes this digital file as described, for example, with reference to Figure 3 to detect untimely switching.

Generator variants:

Alternatively, the generator may exhibit hysteresis. For this, the thresholds S ¹ and S ² described above have different values.

The generator 20 is not necessarily a detector of a physical quantity. In practice, the generator 20 can be any electronic circuit that generates a discrete electrical signal at one of its outputs. For example, the generator may be a pulse width modulator. In this case, the signal SE ^g is an electrical signal modulated according to the principle of pulse width modulation, also known by the acronym PWM (“Pulse Width Modulation”). In this case, the duration of the interval A3.1 or A3.2 is less, and preferably at least two times less, than the duration of the smallest pulse that this modulator can generate. In another example, the generator is a clock and the signal SE ^g is a periodic discrete electrical signal that includes periodic rising or falling fronts.

In another example, the generator is an analog out-of-range value detector. For example, the allowed value range for the analog signal is [Sb; Sh]. In this case, the generator includes two comparators that continuously compare the value of the analog signal, respectively, with the high threshold Sh and with the low threshold Sb. As soon as one of these thresholds is crossed, the generator modifies the state of the signal SE ^g .

In the case that the physical magnitude is a mechanical displacement of a part, the transducer 40 is for example a simple switch moved by this part between an open state in which the electrical resistance of the transducer 40 takes a value R ¹ and a state closed in that this electrical resistance takes a different value R ² . In this case, the comparator 42 can be replaced by a simple potential difference applied between the terminals of the switch and connecting the output 36 to one of its terminals.

If the physical quantity to be measured is an electrical physical quantity, the transducer 40 can be omitted.

The signal SE ^g can also be a current, supplied or absorbed by the generator. In particular, the generator can vary the intensity of a current absorbed between two stable states by modifying, for example, its internal resistance. The generator may also include a current source capable of varying the intensity of the supplied current between two stable states. In these cases, each stable state corresponds to a different intensity of this current. Everything that has been described here also applies to such a signal SE ^g . For example, for this, step 60 of The shape further converts the intensity of the signal SE ^g into a corresponding voltage before transmitting the signal SE ^mef to steps 62 and 64.

Other variants:

In a variant, the supply stage is common to the generator 20 and the module 22. For example, the stage 24 also supplies the module 22. In this case, the stage 26 can be omitted.

The electronic device may be installed and used anywhere other than an aircraft. For example, it can also be installed inside a car or railway vehicle. It can also be installed in fixed environments, such as inside a nuclear power plant or a residence or factory.

Chapter IV: advantages:

The inventors have observed that the wear of the electronic components and the printed circuit is the cause of untimely switching in the electrical signal generated by the generator and this generally long before this generator breaks down definitively. Furthermore, since these untimely switches of the signal SE ^g are very short, they often go unnoticed and generally do not disturb the operation of the processing system 56. The self-diagnosis modules described here make it possible to detect these untimely switchings and signal them. Since then, it is possible to report a generator failure long before it breaks down permanently. Furthermore, the electronic device is simple to make because it only uses a timer and a comparator to detect a generator failure. In particular, the self-diagnosis module does not use an integrator or shunt to detect a generator failure. Finally, unlike certain known self-diagnosis modules, the untimely switching detected here is not generated voluntarily to test the correct operation of the generator. Therefore, the self-diagnosis module is devoid of a generator of untimely switching and does not use such voluntarily generated untimely switching.

The fact of using a power supply stage to power the generator different from the one used to power the self-diagnosis module also makes it possible to detect untimely switching caused by the aging and wear of stage 24. On the other hand, this makes it possible to have an electronic block, formed by the self-diagnosis module and its power stage, which can be on-board or remote.

Claims (9)

1. Set including: - an electronic device equipped with a self-diagnosis function, including this device: - a generator (20) adapted to generate at an output a discrete electrical signal that can only assume, at a given time, a single stable state from among a discrete set of possible stable states, said discrete set being chosen from the group consisting of a discrete set of a plurality of stable voltages and a discrete set of a plurality of stable current intensities, this discrete set of possible stable states including a predetermined first and a second stable state, - a self-diagnosis module (22; 120) capable of generating an error signal that indicates a failure, this self-diagnosis module being capable of: - to generate this error signal when connected only to the generator output, and - activating a timer in response to the passage of the discrete electrical signal from the first stable state to another state, the timer counting down a predetermined time interval from the moment it is activated, characterized by: - the self-diagnosis module (22; 120) is also suitable: - at the instant when the time interval discounted by the timer has elapsed, to compare the current state of the discrete electrical signal with the first stable state, and - if the current state is equal to the first stable state, to cause the generation of the error signal and, alternatively, if the current state is different from the first stable state, to inhibit this activation of the error signal, and - the set also includes an electronic signal processing system (56) capable of taking advantage of the error signal generated by the self-diagnosis module to indicate to a maintenance operator that the generator presents precursor signs of failure. 2. Assembly according to claim 1, wherein the electronic device includes: - a first stage (24) for powering the generator capable of generating, from a potential difference, the voltage and current necessary for the operation of the generator, and - a second power supply stage (26) for the self-diagnosis module capable of generating, from the same potential difference, the voltage and current necessary for the operation of the self-diagnosis module, this second power supply stage being different and independent of the first feeding stage. 3. Assembly according to any one of the preceding claims, wherein the generator (20) is a detector of a physical quantity and the discrete electrical signal: - takes the first stable state when the physical magnitude crosses, in one sense, a first predetermined threshold, and alternatively - takes the second stable state when the physical magnitude crosses, in the opposite direction, a second predetermined threshold. 4. Set according to any one of the preceding claims, wherein the discrete set of several possible stable states comprises only the first and second stable states. 5. Assembly according to any one of the preceding claims, wherein the device comprises a single box (50) within which the generator and the self-diagnosis module are housed. 6. Assembly according to any one of the preceding claims, wherein the self-diagnosis module comprises: - a monostable scale (U3.1, U3.2) that includes an input and an output (Q) through which a clock signal is emitted, the input being connected to the output of the generator so that it receives a rising front or descending every time the discrete electrical signal generated by the generator passes from the first stable state to the other state, this scale being suitable to generate at its output, in response to the ascending or descending front received at its input, an ascending or descending front in the clock signal at the instant at which it has elapsed the time interval discounted by the timer, thus forming this monostable scale said timer, and - a JK scale (U4.1, U4.2) including: • a first input connected to the output of the generator to receive an electrical signal representative of the current state of the discrete electrical signal generated by the generator, • a second input permanently connected to an electrical signal representative of the first stable state, • a third input connected to the monostable scale output (U3.1, U3.2) to receive the clock signal, • an output (70) that generates the error signal, This JK scale is suitable: - in response to said rising or falling front in the clock signal, to compare the current states of the electrical signals received at its first and second inputs, and - if, at that instant, the current states of the electrical signals received at the first and second inputs are equal, to activate the generation of the error signal at their output and, alternatively, if the current states of the electrical signals received at The first and second inputs are different, to inhibit this activation of the error signal. 7. A self-diagnosis module (22; 120) for an assembly according to any one of the preceding claims, wherein the self-diagnosis module is capable of activating a timer in response to the passage of the discrete electrical signal from the first stable state to another. status, counting this timer a predetermined time interval from the moment it is activated, characterized in that the self-diagnosis module is also suitable: - at the instant when the time interval discounted by the timer has elapsed, to compare the current state of the discrete electrical signal with the first stable state, and - if the current state is equal to the first stable state, to activate the generation of the error signal and, alternatively, if the current state is different from the first stable state, to inhibit this activation of the error signal. 8. Self-diagnosis procedure for an electronic device, said electronic device including a generator capable of generating at an output a discrete electrical signal that can only take, at a given instant, a single stable state from among a discrete set of possible stable states, This discrete set being selected from the group consisting of a discrete set of several stable voltages and a discrete set of several stable current intensities, this discrete set of possible stable states including a first and second predetermined stable states, this procedure including activation ( 84,90) a timer in response to the passage of the discrete electrical signal from the first stable state to another state, said timer counting down a predetermined time interval from the moment it is activated, characterized in that this procedure also includes the following stages: - at the instant in which the time interval discounted by the timer has elapsed, the comparison (86, 92) of the current state of the discrete electrical signal with the first stable state, and whether the current state is equal to the first stable state, activating (88, 94) the generation of the error signal and, alternatively, if the current state is different from the first stable state, inhibiting this activation of the error signal, and - an electronic signal processing system (56) indicates, taking advantage of the error signal generated by the self-diagnosis module, to a maintenance operator that the generator shows precursor signs of failure. 9. Information recording support (124) readable by a microprocessor, characterized in that this information recording support includes instructions for executing a procedure according to claim 8, when these instructions are executed by the microprocessor.